Best Answer
(As Selected By nanadjei2)

when you sync multiple relations you need to pass an associative array as an first argument. Say, I want to attach tags with id 1,2,3 along with the pivot data slug as some-slug for each of the record:

when you sync multiple relations you need to pass an associative array as an first argument. Say, I want to attach tags with id 1,2,3 along with the pivot data slug as some-slug for each of the record: